Listless, a.
Etymology: [OE. listles, lustles. See Lust.]
Having no desire or inclination; indifferent; heedless; spiritless. " A listless unconcern." Thomson. Benumbed with cold, and listless of their gain. Dryden. I was listless, and desponding. Swift.
Syn. -- Heedless; careless; indifferent; vacant; uninterested; languid; spiritless; supine; indolent. -- List"less*ly, adv. -- List"less*ness, n.
Shades of meaning
Fernald has no entry of its own for listless; he lists it under abstracted, faint.
Where he writes about it:
A preoccupied person may seem listless and thoughtless, but the really listless and thoughtless have not mental energy to be preoccupied. — from abstracted
A person may be faint when physically wearied, or when overcome with fear; he may be a faint adherent because naturally feeble or purposeless, or because half-hearted in the cause; he may be a faltering supporter because naturally irresolute or because faint-hearted and timid in view of perils that threaten, a listless worker, through want of mental energy and purpose. — from faint